Allow users to specify quality=None (#65)

* Add a test that showcases that the quality=None parameter is ignored

* Allow for quality to be none

Author: hmaarrfk

imageio_ffmpeg/_io.py

@@ -341,7 +341,6 @@ def write_frames(
     pix_fmt_in = pix_fmt_in or "rgb24"
     pix_fmt_out = pix_fmt_out or "yuv420p"
     fps = fps or 16
-    quality = quality or 5
     # bitrate, codec, macro_block_size can all be None or ...
     macro_block_size = macro_block_size or 16
     ffmpeg_log_level = ffmpeg_log_level or "warning"
@@ -364,8 +363,9 @@ def write_frames(
     assert isinstance(pix_fmt_in, str), "pix_fmt_in must be str"
     assert isinstance(pix_fmt_out, str), "pix_fmt_out must be str"
     assert isinstance(fps, floatish), "fps must be float"
-    assert isinstance(quality, floatish), "quality must be float"
-    assert 1 <= quality <= 10, "quality must be between 1 and 10 inclusive"
+    if quality is not None:
+        assert isinstance(quality, floatish), "quality must be float"
+        assert 1 <= quality <= 10, "quality must be between 1 and 10 inclusive"
     assert isinstance(macro_block_size, int), "macro_block_size must be int"
     assert isinstance(ffmpeg_log_level, str), "ffmpeg_log_level must be str"
     assert isinstance(ffmpeg_timeout, floatish), "ffmpeg_timeout must be float"

tests/test_io.py

@@ -254,14 +254,18 @@ def test_write_wmv():
 
 @no_warnings_allowed
 def test_write_quality():
+    try:
+        import numpy as np
+    except ImportError:
+        return skip("Missing 'numpy' test dependency")
 
     sizes = []
     for quality in [2, 5, 9]:
         # Prepare for writing
         gen = imageio_ffmpeg.write_frames(test_file2, (64, 64), quality=quality)
         gen.send(None)  # seed
         for i in range(9):
-            data = bytes([min(255, 100 + i * 10)] * 64 * 64 * 3)
+            data = np.random.randint(0, 255, (64, 64, 3), dtype="uint8")
             gen.send(data)
         gen.close()
         with open(test_file2, "rb") as f:
@@ -270,7 +274,29 @@ def test_write_quality():
         nframes, nsecs = imageio_ffmpeg.count_frames_and_secs(test_file2)
         assert nframes == 9
 
-    assert sizes[0] < sizes[1] < sizes[2]
+    assert sizes[0] <= sizes[1] <= sizes[2]
+
+    # Add a test compression with lossless mode with ffmpeg
+    gen = imageio_ffmpeg.write_frames(
+        test_file2,
+        (64, 64),
+        # Setting the quality to None should disable
+        # any premade settings
+        quality=None,
+        output_params=["-qp", "0"],
+    )
+    gen.send(None)  # seed
+    for i in range(9):
+        data = np.random.randint(0, 255, (64, 64, 3), dtype="uint8")
+        gen.send(data)
+    gen.close()
+    with open(test_file2, "rb") as f:
+        size_lossless = len(f.read())
+    # Check nframes
+    nframes, nsecs = imageio_ffmpeg.count_frames_and_secs(test_file2)
+    assert nframes == 9
+
+    assert sizes[2] < size_lossless
 
 
 @no_warnings_allowed